Contrast Oral Radiology

22/02/2024

Florid cemento-osseous dysplasia

Radiopaque/high-density bone structure noted in tooth bearing regions. If found in multiple quadrants of the jaws, it would be referred to as florid (versus periapical or focal cemento-osseous dysplasia). This 30 year old F noted pain in the lower left quadrant.

Case from Radiopaedia rID 180448
https://radiopaedia.org/cases/180448

19/02/2024

Radiation dose in CBCT

When delving into CBCT, the effective dose is contingent on many factors like field of view, resolution, kVp, mA, time, low or high dose protocols, and the specific models themselves.

For the Carestream CS 9300
- A 5 x 5cm adult low-dose CBCT scan has an effective dose of 3 µSv, or 8.5 hours worth of equivalent background radiation
- A 10 x 10cm dual-jaw CBCT scan has an effective dose of 75 µSv, or 9 days worth

For the Planmeca ProMax 3D Classic
- A 4 x 5 cm has an effective dose of 13 µSv, or 1.5 days worth
- A 8 x 8 cm has an effective dose of 36 µSv, or 4 days worth.

Increasing the field of view results in increased effective dose. Furthermore, image quality and effective dose are also interconnected. For superior spatial resolution and better visualization of fine details, effective dose must increase.

Protecting patients and limiting necessary radiation dose is a paramount duty. The principles of ALARA/ALADA apply when prescribing radiographs. Selection criteria and using the right parameters for CBCT scans should adapt depending on the patient and purpose at hand.

16/02/2024

Understanding radiation dose

Radiation doses from routine dental imaging often raise questions and concerns among patients. More and more dentists are also using advanced dental imaging techniques too, which could have increased radiation doses.

The effective dose is the primary metric for describing radiation dose, as it factors in tissue weighing in the human body and signifies the probability of stochastic, or cancer-causing, effects. This can be compared to background radiation equivalent time, or low levels of radiation exposure from non-intentional radiation sources.

On average, an FMX with a digital (CCD) sensor using rectangular collimation has an effective dose of 20 microsieverts (µSv), equivalent to 2.5 days of background radiation. A panoramic radiograph has an effective dose of 20 µSv, also equivalent to 2.5 days of background radiation.

Effective doses do vary depending on many factors such as film vs PSP vs digital sensors, kVp, mA, time, and the x-ray machines themselves.

14/02/2024

Exploring Stafne Defects

Ever heard of a Stafne defect? It's seen every now and then and can be confusing if mistaken for pathology. The Stafne defect, AKA Stafne bone cavity, is a non-pathological condition where a lingual cortical depression occurs in the mandible, typically in the posterior region near the angle of the jaw.

What makes it unique? Unlike traditional cysts, a Stafne defect isn't caused by cystic growth or inflammation. Instead, it's believed to be a developmental anomaly where salivary gland tissue gets displaced during embryonic development, leading to a concavity in the bone.

But here's the kicker. Stafne defects are usually asymptomatic and discovered incidentally during routine dental imaging, like panoramic radiographs or CBCT scans. Further investigation/treatment is not required. Understanding Stafne defects helps dental professionals differentiate them from other lesions and avoid unnecessary treatment.

12/02/2024

Ways to reduce metal artifacts in CBCT scans

For patients with many restorations or implants, reducing the amount of metal artifact can lead to more diagnostic scans.

Here are some tips:
- Keeping the metal object out of the field of view. This is most helpful if you're taking a small volume (ie: endo scans), and you have an implant in the region. If it's possible to keep the implant out of the field of view, the amount of metal artifact is actually significantly reduced (Andrade-Bortolleto, 2024)
- Check patient positioning. If the scan is for implant purposes, ensure the occlusal plane is horizontal so that metal from restorations stay confined to the occlusal area, without affecting analysis of the alveolar bone.
- Cautiously applying metal artifact reduction algorithms. This can reduce the amount of degradation and scatter. However, excessive use may result in loss of detail.

Check out the example of HDX Will's PrecisionMAR algorithm and how it worked for metal artifacts from orthodontic appliances. Images taken from HDXwillna.com

www.contrastoralradiology.com

08/02/2024

Metal Artifact Alert!
Metal and other high-density materials in a patient's mouth can obscure details on the CBCT. Notice how the crowns here cause streaks on the axial views? Compare it with the other axial view without the streaks.

Unfortunately, if your patient has a lot of metal restorations or implants, it's challenging to discern small details due to the artifact. Depending on your CBCT machine, you can apply metal artifact reduction algorithms to which reduce the appearance and smoothen out the image. Be wary though, because applying too much metal artifact reduction may also reduce the diagnostic quality of the scan!

31/01/2024

When should you take a small versus large field of view?

A small FOV is ideal for precise assessments of specific areas, relatively reducing radiation exposure and enhancing image resolution. It's perfect for single-tooth evaluations and localized pathology detection. On the other hand, a large FOV showcases more of the head and neck, capturing comprehensive anatomical structures essential for orthodontic assessments, maxillofacial surgeries, and implant planning. Large FOV scans facilitate comprehensive treatment planning and interdisciplinary collaboration.

Dentists must carefully consider the clinical requirements, patient considerations, and diagnostic objectives when deciding between a small and large FOV. By leveraging the capabilities of CBCT technology judiciously, practitioners can optimize treatment outcomes and elevate patient care to unprecedented levels of excellence.

Check out our blog entry describing selection of the right field of view in Cone Beam CT imaging for enhanced dental diagnostics and treatment planning!

In the realm of modern dentistry, technology continues to revolutionize diagnostic and treatment capabilities. Among the notable advancements, Cone Beam Computed Tomography (CBCT) stands out as a pivotal tool, offering three-dimensional imaging with remarkable clarity and precision. One crucial aspe...

23/01/2024

Unlock the full potential of your CBCT machine with our free e-book! Download now and discover expert tips to achieve high-quality scans, regardless of your equipment type.

In this new complimentary e-Book, we share immediate and actionable tips to achieve the best quality scans from your CBCT machine. We explain when to use specific parameters and settings, how to prepare and position your patients in the machine, and how to limit motion artifact, beam hardening artif...